Luminous Landscape Forum
Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: Doug Peterson on February 10, 2014, 06:42:59 pm
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(http://www.doug-peterson.com/download/temp-for-DT/X25_IQ250_47XL_186-192-201-205_Stitch-630.jpg)
Phase One IQ250 Tech Camera Testing (https://digitaltransitions.com/blog/dt-blog/phase-one-iq250-tech-camera-testing)
Go crazy guys. Ask questions. Tear the files apart. Find the good. Find the bad. Let me know what you think of my effective image circle evaluations - they are very much a work in progress.
I'm going to try my best NOT to be online tonight. Bit burnt out - I worked all weekend and then sat on a tarmac for 3 hours yesterday - the entire time I was working on processing and working up this test.
We have a few more tests captured, including a great ISO sweep at this same location (I say great because it's a good location for an ISO sweep - lots of dark and light tones, lots of fine detail, lots of color) but it will probably be a few more days before I get to post them as we have an IQ250 Open House (https://digitaltransitions.com/event/event/phase-one-iq250-launch-nyc) in NYC on Wednesday that I have to help prep.
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Go crazy guys. Ask questions. Tear the files apart. Find the good. Find the bad. Let me know what you think of my effective image circle evaluations - they are very much a work in progress.
I'm going to try my best NOT to be online tonight. Bit burnt out - I worked all weekend and then sat on a tarmac for 3 hours yesterday - the entire time I was working on processing and working up this test.
Hi Doug,
Just wanted to express my appreciation for the work you've done, sofar (http://www.luminous-landscape.com/forum/Smileys/default/wink.gif), thanks. I'll have a look at the results after getting some sleep myself.
Cheers,
Bart
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+1!
Thank's a lot!
Erik
Hi Doug,
Just wanted to express my appreciation for the work you've done, sofar (http://www.luminous-landscape.com/forum/Smileys/default/wink.gif), thanks. I'll have a look at the results after getting some sleep myself.
Cheers,
Bart
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+2 Thanks for the work.
Curious why the 60 behaved so badly when it works well very well on the 160/260 and 280.
Will the Rod 28 be tested in the future?
Also just wanted to double check, the crop factor would make the 40mm effectively a 52mm on the 250?
Paul C
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Another thank you Doug!
Also just wanted to double check, the crop factor would make the 40mm effectively a 52mm on the 250?
Paul C
Yes that's right if you are comparing it to a 53.7 x 40.4mm sensor. A 40mm on an IQ260/80 is 26mm in 135 format (24x36mm). A 40mm on an IQ250 is 31.5mm in 135 format.
Dave
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Thanks Don
I was comparing it to the full frame 160/260 and 280 sensor. Love what I see with the 250 but the crop is a issue for me as I want/need the wider the better.
Paul C
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Splendid building!
Very interesting tests, thanks for taking the time to perform this.
Cheers,
Bernard
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If I had a truckload of money you would be getting it. but I dont. anyone need a kidney?
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The 60mm difference in performance in my opinion, gets back to the micro lens issue and how the image is projected and received by the sensor.
The 60mm is sort of a transitional lens from a traditional, wide angle focal length lens, to a normal configuration, which starting at 70mm move towards a normal lens in design philosophy. Normal lenses and longer focal lengths, generally project a much flatter, physically, image shape. This is easier for any sensor to accept.
A retest and perhaps, a test at other apertures such as even F16 might be in order.
There are some interesting lens phenomonon's, with various lenses. The 47mm APO-Digitar XL, for example, is not stellar with 80mp backs in most cases, yet is more than adequate up close, for still life at F16(!) and on 80mp backs. The longer focal lengths say 120mm and longer generally do better stopped down a bit further even at F16 with 80mp backs.
The 60mm XL may prove to be one of those which just has an eccentric way of performing with some digital backs.
Anyway, Doug did a fantastic job, and we all owe him a heartfelt thanks for his in depth, hard work on this test. Thanks again, Doug.
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Thanks for this Doug, and great to publish the raw files, I'm very grateful!
The IQ250 files can be processed in RawTherapee by the way, but probably there need to be some matrix fixing before getting full support.
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Hi,
Absolutely agree! Thanks for the effort!
Best regards
Erik
Thanks for this Doug, and great to publish the raw files, I'm very grateful!
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Thanks for this Doug, and great to publish the raw files, I'm very grateful!
The IQ250 files can be processed in RawTherapee by the way, but probably there need to be some matrix fixing before getting full support.
How? I tried adding eip extension, no go. Changing it to iiq didn't work either.
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How? I tried adding eip extension, no go. Changing it to iiq didn't work either.
The .eip files are ordinary zip archives, unzip (rename to .zip if required) and search for the 0.IIQ file. RT is a bit buggy with files called the same name (can't have two open with same name) so if you unpack several .eip rename the 0.IIQ to different names.
I'm going to look more at the files and do some analysis but I just got a hard disk failure :-\ so I'm recovering stuff
With RawTherapee you get some pretty bad mazing in the demosaicing for shifted areas on the wides. When I get some time again I'll try to figure out why. Probably it's a side effect of pixel vignetting which Capture One is better at hiding.
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Many thanks Doug, and kudos for all the time and effort - very much appreciated
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A quick look with rawdigger on HR32 LCC (Rodenstock Digaron-W 32mm) it seems like about 3.5 stops of the signal is lost from center to the edge of the 90mm image circle, and there's no major difference between the channels. Can't guarantee I've calculated the offsets right though :-).
It doesn't seem to be as bad as I expected.
Was a center filter used on the 32mm?
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A comment on shooting apertures; f/9 is quite wide.
The Scheider 35 XL and Schneider 47 XL is optimized for f/11, and my preference is that for larger shifts you stop them down further to f/16 to get more even center vs corner sharpness.
The Rodenstocks do f/9 well, but my personal taste is towards f/11 anyway to reduce aliasing and false colors and get a more workable depth of field. Anyway different shooters have different tastes regarding this and there are many that would prefer f/9 so the test is fine. If one does prefer f/9 the SK35XL and 47XL is not the lenses to use though.
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Very nice test Doug!!
Thank you :)
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Doug, you wrote:
"Processing/Color: Processing of the composite files was done in Capture One v7. White balance, which is hard to determine in a mixed-light moody scene like this was set roughly during processing to attempt to match the several backs and lenses in the same ballpark - however, this is an imperfect process especially as some of the lens+back combinations had uncorrectable color cast. We do not recommend this test be used to evaluate the subtle differences in color between these three backs (we will have more testing specific to color coming soon)."
Which lens/back combinations had in correctable color casts?
What are your recommendation for the max shift with the IQ250/40mm Rodenstock combination?
Thanks
Paul C
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What are your recommendation for the max shift with the IQ250/40mm Rodenstock combination?
There's a table for that in the link, 90mm image circle is recommended, ie the full official image circle can be used.
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Curious why the 60 behaved so badly when it works well very well on the 160/260 and 280.
I am too! I hope to do more IQ250 and 60XL testing at additional apertures and with more exposure variation, but not soon.
Will the Rod 28 be tested in the future?
I hope to add the Schneider 43XL and a longer lens to our testing sometime but the 28HR is not on my list largely because we don't have and don't plan to have one in our demo/rental inventory. If you (or any other 28HR owner) happen to be in NYC, Texas, or Vegas at our upcoming events (https://digitaltransitions.com/event/event) then I could try to coordinate such a test.
Also just wanted to double check, the crop factor would make the 40mm effectively a 52mm on the 250?
You can use our visualizer to compare the IQ250 and IQ260 for effective focal lengths (https://digitaltransitions.com/page/tech-camera-visualizers). You can use the lower version (the beta) to compare with and without stitching images.
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The IQ250 files can be processed in RawTherapee by the way, but probably there need to be some matrix fixing before getting full support.
Iridient Raw Developer (http://www.iridientdigital.com/products/rawdeveloper.html) can also open IQ250 files as of their latest version. They also natively support EIP files, so no need to extract them. It seems to handle the Mazing in some of the extreme combinations (e.g. 30mm rise and 15mm shift with the 60XL on IQ250) better even than C1.
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It doesn't seem to be as bad as I expected.
Was a center filter used on the 32mm?
A Center Filter was NOT used. I'll add some notes to the test page to that effect.
I'm also adding a statement in our summary that users that previously did not use center filters might want to consider them in light of the larger amount of light fall off we see in the IQ250, but that this might be offset by the increased ability to recover shadows in the IQ250.
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Doug, thanks for doing this incredible amount of work !
I had a couple of questions:
- How did you manage to keep track of all the settings for ach picture through the shoot ? Since there is only partial exif on tech cams, you must have had a way to assign the aperture / movements / lens used to each image. Was it simply a notebook / excel with notes associated to each file (filename displayed on the back) ? Or did you shoot tethered, and then filled in the exif after each shot ? Or something more clever ?
I'd like to do some tests on my own, but keeping track of things is a bit tricky.
- You say on DT web-page that you shot the LCCs later. This means that setting the aperture back to f/9 is repeatable enough ? There are not click stops for the aperture on the shutter, so I've been a bit suspicious of doing the LCC later (as you can not be 100% certain you come back exactly to the same aperture - could be 9.2 or 8.8).
Thanks again for this testing !
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Doug, you wrote:
"Processing/Color: Processing of the composite files was done in Capture One v7. White balance, which is hard to determine in a mixed-light moody scene like this was set roughly during processing to attempt to match the several backs and lenses in the same ballpark - however, this is an imperfect process especially as some of the lens+back combinations had uncorrectable color cast. We do not recommend this test be used to evaluate the subtle differences in color between these three backs (we will have more testing specific to color coming soon)."
Which lens/back combinations had in correctable color casts?
What are your recommendation for the max shift with the IQ250/40mm Rodenstock combination?
35XL and IQ280 and IQ250 was the worst offender regarding uncorrectable color casts. In these combinations the LCC routine was not able to restore high fidelity color to the effected areas.
This is not a new finding, and is one of the reasons we started recommending Rodenstock wides on a near exclusive basis for the IQ180.
The table of max usable image circles in the link can be used with our visualizer (https://digitaltransitions.com/page/tech-camera-visualizers) to determine max movements, which depends on orientation of the sensor and how much you care about the extreme corner of the image (e.g. if there is featureless sky or featureless white ceiling in the extreme corner you may be okay with several more mm of movement). In the case of the IQ250 and 40HR I found acceptable results with a 90mm IC (the same as stated by the manufacturer) which according to our visualizer means between 20mm and 25mm of rise could be used on a horizontal frame.
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- How did you manage to keep track of all the settings for ach picture through the shoot ? Since there is only partial exif on tech cams, you must have had a way to assign the aperture / movements / lens used to each image. Was it simply a notebook / excel with notes associated to each file (filename displayed on the back) ? Or did you shoot tethered, and then filled in the exif after each shot ? Or something more clever ? I'd like to do some tests on my own, but keeping track of things is a bit tricky.
Shot tethered and used the Next Capture Naming to keep track. I made one mistake - the 60XL on one of the backs I did [top-right > top-center > top-right] meaning I missed the [30mm rise 15mm left] combo. Still kicking myself about that.
- You say on DT web-page that you shot the LCCs later. This means that setting the aperture back to f/9 is repeatable enough ? There are not click stops for the aperture on the shutter, so I've been a bit suspicious of doing the LCC later (as you can not be 100% certain you come back exactly to the same aperture - could be 9.2 or 8.8).
The Schneiders have clickstops, the Rodenstocks do not.
In other testing and past experience an LCC is not as sensitive as you might think. Being off by a mm of movement, or a fraction of a stop, or a small change in focus is not of real-world consequence. Obviously if you're off by several mm of movement, a large change in aperture or focus does matter. Also I wanted this to be as real-world as possible; whatever quality of results I could get in this test I fully expect photographers to get at least that good of results (or better) when faced with real world challenges. In the real world photographers are careful about setting aperture and movement the same for the LCC, but not scientifically precise about doing so.
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It seems to handle the Mazing in some of the extreme combinations (e.g. 30mm rise and 15mm shift with the 60XL on IQ250) better even than C1.
I shall try to figure out the reason why mazing occurs (edit: found the reason, read below).
With RawTherapee one can select different demosaicers and it depends on type how bad it becomes, the types that try to extract the most details get most issues with mazing. It becomes so bad it's unusable, even colors fail, see attached image. While a VNG4 demosaicer provides a smooth result.
I'm no demosaic expert, but my layman's guess so far is that it's because there different amount of pixel vignetting on the greens, ie there's some difference between G1 and G2 and many demosaicers expect that they should have the same amplification. VNG4 is an algorithm that assumes G1 and G2 are different, but can't extract as much fine detail as many of the others.
Edit: looking at the raw values I can confirm that G1 and G2 channels start to differ, and the difference increases further out. The example crop is 30mm out and there G1 is about 1/3 stop weaker than G2. Without shift the G1 and G2 has the same amplification and the image also demosaics well. That G1 and G2 vignettes differently makes it more complicated to do flatfield correction (=apply LCC), but Capture One has obviously an algorithm that can handle it quite well. It shall be interesting to test in my own Lumariver HDR but I need to fix some stuff before IQ250 files can be opened there.
RawTherapee's current flatfield correction algorithm can't handle this situation at all, while it works well for the CCDs I've tested (I use it all the time with my Aptus 75), so I'm assuming the CCDs vignette more evenly on G1 and G2.
Note to bayer array newcomers if you're confused with my notion of Green1 and Green2: there are two greens for each red and blue pixel, usually both greens have the same amplification, but in some cases they can differ. With this sensor it seems to be that amplification indeed is the same, but angular response is different causing variations over the sensor when wide angle lenses are shifted. The pattern of this variation would be interesting to investigate. Hopefully they're smooth, because if there are small spotty variations in angular response it will be hard to correct well without smearing detail or losing color stability.
This sensor seems like a very interesting challenge on tech cam wides. With proper algorithms one can probably get quite good results with the wides (one can afford to lose a few stops with this supreme dynamic range), but if algorithms are not doing the best the result can be a disaster.
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The table of max usable image circles in the link can be used with our visualizer (https://digitaltransitions.com/page/tech-camera-visualizers) to determine max movements, which depends on orientation of the sensor and how much you care about the extreme corner of the image (e.g. if there is featureless sky or featureless white ceiling in the extreme corner you may be okay with several more mm of movement). In the case of the IQ250 and 40HR I found acceptable results with a 90mm IC (the same as stated by the manufacturer) which according to our visualizer means between 20mm and 25mm of rise could be used on a horizontal frame.
I looked at the visualizer, but still can't tell on shift. What I am wondering is with the 40mm Rodenstock, which artificially vignettes due to the design by Rodenstock at 16mm on a 260/160/180 etc. full frame. Will the 40mm on the 250 go to say 20mm or even 25mm before hitting the artificial vignette? Or do you suffer too much from light fall off since the 40mm has no CF.
Just curious. I know you are taxed at the moment. My same thoughts apply to the 28mm which eve though has only a 70mm IC, it may shift to 15mm or 12mm on the 250 since it won't see the artificial vignette as fast as the full frames will.
Paul
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I looked at the visualizer, but still can't tell on shift. What I am wondering is with the 40mm Rodenstock, which artificially vignettes due to the design by Rodenstock at 16mm on a 260/160/180 etc. full frame. Will the 40mm on the 250 go to say 20mm or even 25mm before hitting the artificial vignette? Or do you suffer too much from light fall off since the 40mm has no CF.
Just curious. I know you are taxed at the moment. My same thoughts apply to the 28mm which eve though has only a 70mm IC, it may shift to 15mm or 12mm on the 250 since it won't see the artificial vignette as fast as the full frames will.
Maybe you missed that you can click and drag the sensor to the left or right in the visualizer?
With the 40mm a horizontally mounted IQ250 you will hit a hard vignette in the two outside corners of the frame at almost exactly 20mm of shift. But at 18mm of shift you'll be entering the mush/low-fidelity area of the image circle. So I'd only use 20mm of shift when the image content and colors in the corners is not that important.
28HR I can't tell you how much movement since I haven't tested. From the specs it should be 9mm of shift before you hit the hard edge.
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I've looked more at the IQ250 32HR jpeg. Maybe I was wrong when I said it wasn't as bad as I thought.
I think the library is great to show detail in the shifted area, but it probably masks (lack of) color stability quite a bit. It seems to me that already outside the 60mm frame the LCC has difficulty in correcting color, which would be visible in a more evenly colored ceiling.
I also see just above the "15mm Rise" label the next section getting stitched in and it has severe mazing artifacts as discussed above (probably due to different G1/G2 pixel vignetting).
From that image I'd say that the 32HR usable image circle is likely to be 60mm rather than 80mm that shows in Doug's table. You can compare the IQ260 and IQ250 32HR file side by side then it becomes more obvious that the IQ250 loses color stability rather quickly.
A sanity check experiment one can do is to LCC-correct the LCC shot with itself. If that is not a perfectly uniform surface afterwards then it's just too much vignetting/color cast to be fully corrected.
Some subjects can work with some residual color cast, this library ceiling for example can swallow more than a clear blue sky, but I think a recommendation of usable image circle should be defined as zero visible color cast even if you photograph a clear blue sky or a large white wall.
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I did not experience any mazing problems with the basic raw file in RT.
Thanks Doug for providing the raw for testing.
Here is a copy converted in RT 4.0.11.79. I tried the newer .12 version, it is a buggy mess that crashes. Stay away until it is revised. .11.79 is stable.
http://farm3.staticflickr.com/2806/12463985743_f1c563964f_o.jpg (http://farm3.staticflickr.com/2806/12463985743_f1c563964f_o.jpg)
The amount of detail in 1 shot is impressive. I did not like the colors especially green, showing up on the bars. That must be particular to the No AA plus that lens.
The DR is very good. Having the daylight of the window shows that off even with a different color temp.
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Try the shifted ones, that's where the G1 vs G2 problem occurs and you get mazing. The unshifted that you have converted so nicely has no mazing issue (I've tested that too).
The high amount of false colors (greens on the bars etc) is also showing the the Capture One conversion, it's an aliasing artifact. Stopping down to f/11 had probably been a better choice for this subject, maybe even more. Some prefer uber-crisp images and manually clean up moire/false colors though, while I prefer stopping down to kill most problems with diffraction and then sharpen up.
You can try experimenting with the "false color supression steps" in the raw tab of raw therapee to reduce false colors, if you've not already done that.
I did not experience any mazing problems with the basic raw file in RT.
Thanks Doug for providing the raw for testing.
Here is a copy converted in RT 4.0.11.79. I tried the newer .12 version, it is a buggy mess that crashes. Stay away until it is revised. .11.79 is stable.
http://farm3.staticflickr.com/2806/12463985743_f1c563964f_o.jpg (http://farm3.staticflickr.com/2806/12463985743_f1c563964f_o.jpg)
The amount of detail in 1 shot is impressive. I did not like the colors especially green, showing up on the bars. That must be particular to the No AA plus that lens.
The DR is very good. Having the daylight of the window shows that off even with a different color temp.
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32HR Jpgs: i'm shocked by the noise of the iq260 in the shifted areas (over 5mm) left and right. the iq250 is almost noise free, although the image appears to be half a stop shorter exposed. highlights rock on iq250 too, clear advantage in dynamic range, resolution also better (higher pixel density, ok, but the rodie does deliver). color shift is hard to tell with this setup, would be great to see a test with an overcast sky. doug, when will you do this again outdoors? ;-)
seriously, great work doug, thank you so much!
my next step will be heading out with both of them on an arca rm3di, i think there is no other way to make a buying decision.
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www.silent-moment.com
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color shift is hard to tell with this setup, would be great to see a test with an overcast sky. doug, when will you do this again outdoors? ;-)
In my experience color fidelity is better evaluated with varied and strongly colored subjects than an overcast sky. Alpa did a test with overcast sky that fails to show the color issues I expect would have been shown with a more strongly saturated subject.
We also have done 32HR with IQ250 with strong rise to shoot the Empire State Building with blue sky. I'll be looking at those tests in more detail next week.
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The high amount of false colors (greens on the bars etc) is also showing the the Capture One conversion, it's an aliasing artifact. Stopping down to f/11 had probably been a better choice for this subject, maybe even more. Some prefer uber-crisp images and manually clean up moire/false colors though, while I prefer stopping down to kill most problems with diffraction and then sharpen up.
Selection of f/9 was largely a practical issue of trying to keep exposure times short enough to do the number of back+lens combos I wanted to get through.
Having completed the test, were I to do a paid job shooting this location I'd probably use f/11.
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seriously, great work doug, thank you so much!
my next step will be heading out with both of them on an arca rm3di, i think there is no other way to make a buying decision.
You're welcome!
And yes, I agree, your own test is the best way. As much as I think our test provides useful information there is no replacement for your own testing.
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All you have to do is look at the shifts, forget the center.
The 32mm had no Cf, thus the lightfall off to the shifted edge is not balanced as well as the CF would allow so the LCC is working hard.
NET, the 260, which appears to be shot a ISO140 which is the base for long exposure looks pretty darn bad, excessive noise and really the shift is not useable unless you really down rez the file to around where sensor plus would get you. On center I can get the box where the shadows are pretty harsh to look OK, but as Eric has shown the 250 is cleaner here, but the shift is where the real difference is. Just look at the large wall section to the far left. With the 260 it's all pretty much noise and no structure.
The 260 also has more aliasing on the X frames that cover the books, way more. It's very harsh on the segments where you are looking down them not head on but even head on they appear to be made with beads of different colored material.
The 260 file also shows lots of (way to many IMO) stuck pixels which really surprised me. They are evident anywhere the image is dark or in shade and show up mainly as blue.
The 250 is cleaner throughout, but I feel the transitions of the details are smoother, take a look at the beautiful inlaid vertical strips at the edges, they look much better on the 250, also look under the cases in the middle of the shot, again much cleaner.
On the 250 shift it's got some banding, which I actually have come to expect from this type of pull with CMOS, however you can clean that up.
My net opinion, if all you wanted was a center shot, you can make either test work, however if you were after a FULL RESOLUTION composite, you just can't use the shifted parts of the 260. I didn't look at the right shift as it should be the same. Doug shot these at 2 minutes as I remember so to get a better shifted image on the 260, he would have had to 2x the exposure and maybe do longer, which I believe would have blown the rest of the image out.
Since this is a Sony chip, and I guess the their processor, it's clear that they have a strong advantage in chips. I saw similar results when I first shot the D800 and now it's the same in the MD world. For me it's the noise and lack of use of the shift. If you dig way way way down, you might find a spot where the color is better on the CCD from the 260, but I can't see it.
The 250 file non OE still pulls up very well on the shift.
To keep a 260 is now quite a bit harder a decision to make. I am not a big user of rise and fall, but these pretty much look the same on the 260. I will try to put some images together as Eric did later tonight.
Paul C
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I did every IQ260+32HR file in both ISO50 and ISO140.
I screwed up the naming and two of the six files I listed were actually the ISO140 shots.
For any evaluation of noise I strongly suggest using Capture One. While several programs have support for opening the raw files from the IQ250 nobody else has spent as much time making the files singing, and nobody else uses the dark frame information which is especially important for the IQ260.
I am correcting that now...
Edit: They are now corrected.
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In my experience color fidelity is better evaluated with varied and strongly colored subjects than an overcast sky. Alpa did a test with overcast sky that fails to show the color issues I expect would have been shown with a more strongly saturated subject.
We also have done 32HR with IQ250 with strong rise to shoot the Empire State Building with blue sky. I'll be looking at those tests in more detail next week.
Have you tried applying the LCC on the LCC shot itself? It should be telling. If it doesn't even out, then it's outside the capable range for sure.
Now when I've had a long good look on mainly the 32HR IQ250 shot I think the uncorrectable color casts may be pretty severe, but is somewhat hidden by this subject. Easiest is to show the IQ260 and IQ250 32HR jpeg side by side and compare the color in the ceiling. The IQ250 desaturates and I'm quite sure it has some cast too. I would have to do more tests to be certain though. I haven't tried the LCC on LCC trick myself yet.
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OK, I have calmed down, the iso 50 on the 260 is better, but the 250 still wins on the shifts hands down. (These are not using a CF) It might be closer if I down rez the 60 to 50mp but the iso 50 image could work.
Darn, trying to WB that subject is like a final exam. I appreciate a bit more that the interior shooter go through on a daily basis.
Still don't get why the 260 is showing so many stuck pixels even at iso 50, the dark frame should get those. The 250 has none. The 260 does have a lot of aliasing for sure. Shows clearly on the X frames.
Beautiful building also.
Paul C.
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Thanks very much for this comprehensive first test, Doug. Having just bought an IQ260, I'm slightly depressed to see just how well the IQ250 is controlling noise (and the 260 not, especially shifted). Also I'm really surprised that the IQ250 appears sharper - some of the text on the sign is clearly readable but not so much on the IQ260. Will await the fuller colour tests, but on this evidence CMOS full frame can't come quick enough for me.
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Also I'm really surprised that the IQ250 appears sharper - some of the text on the sign is clearly readable but not so much on the IQ260.
Hi Richard,
The denser sampling pitch of the IQ250's sensor array will extract higher resolution out of the same lens. There may have been focus related issues that additionally contributed, but I assume that Doug tried to keep focus as constant as possible.
Cheers,
Bart
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Here is a copy converted in RT 4.0.11.79.
Note that RT does not have any color matrix for the IQ250 yet, which means that it just uses a default one, I think it assumes (=pretends) the RGB primaries of the camera are the same as sRGB. When we have a proper matrix the default color will be better. The IIQ format does have built-in matrix, but I'm not sure how that should be interpreted, it provides much too saturated color if just used straight away. (RT does not use the built-in matrixes for the IIQ format currently.)
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Thanks very much for this comprehensive first test, Doug. Having just bought an IQ260, I'm slightly depressed to see just how well the IQ250 is controlling noise (and the 260 not, especially shifted). Also I'm really surprised that the IQ250 appears sharper - some of the text on the sign is clearly readable but not so much on the IQ260. Will await the fuller colour tests, but on this evidence CMOS full frame can't come quick enough for me.
Do note that the noise reduction effects the 250 and 260 differently. Feel free to download and play with the raws with different levels of noise reduction.
Also regarding detail rendered keep in mind the IQ250 is doing 50mp in a 1.3 crop, which means each pixel is slightly more "zoomed" in on the subject than the IQ260 which does 60mp in a 1.0 crop. What this means is if you use the same lens the IQ260 will see significantly more of the scene but have just a hair less detail on a particular subject as viewed at 100%. This advantage of the 250 would of course be entirely negated if you chose a slightly wider lens for the 250 to account for the smaller sensor.
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Thanks Doug, good advice. I'll have a play with the raws. Still getting used to the IQ260 after a couple of years with the P45+. They don't seem very different so far, apart from the user interface of course. I bought the Schneider 28XL and have mostly had better results WITHOUT the centre filter, which causes a lot of ghosting and flare and some detail loss. Perhaps the centre filters won't change the results of this test much either.
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Thanks Doug, good advice. I'll have a play with the raws. Still getting used to the IQ260 after a couple of years with the P45+. They don't seem very different so far, apart from the user interface of course. I bought the Schneider 28XL and have mostly had better results WITHOUT the centre filter, which causes a lot of ghosting and flare and some detail loss. Perhaps the centre filters won't change the results of this test much either.
Most of the critiquing of the noise in the 260/280 files has been about the noise in the heavily shifted areas.
With both these backs a multi-second exposure produces excellent results if the file is used as-is, but in both cases pulling up the shadows a few stops (as is the case with the LCC correction of the falloff with several of these lenses) will strain a multi-second file. As you can see with the IQ250 it seems a multi-second file is just as pliable as a short exposure.
Notably the IQ260 can use it's long-exposure mode wherein the amount of noise is increased modestly from native ISO50, but remains more-or-less constant from a short exposure out to a very long exposure. So this shutter speed range (5-10 seconds) is really the one that strains the IQ260 the most - longer than you get IDEAL results out of (you still get very very good results - check out the unshifted image, or request from me one of the shots where I shifted the IQ260 and then changed exposure to adapt for the falloff, lowering the load on the LCC routine) but too short to justify using the Lone Exposure mode.
I suspect if we repeat this test in a sub-second landscape or even a less dim interior that the 260 would hold it's own significantly better.
I also suspect if we had used Center Filters on the 32, 40, 47, and 60 - or changed the exposure for each lens-back position to optimize exposure for that are of the image circle (rather than holding the shutter speed constant) that the results from all the backs would have improved, especially the 260/280. As you say though Center filters come at the cost of having to worry more about flare. The Arca and Cambo compendiums help a lot with that, but there is, regardless an increased hassle factor.
But if nothing else this test shows the 250 can take an absolute beating (multisecond exposure of a mostly-back-lit brown-red wood in the corner of an image circle with heavy fall off) and come out with really strong results. The same can be said of the 260 and 280 in shorter exposures.
If it weren't accumulating 10-15 inches of snow outside (and I weren't' so much a wus) I'd probably be doing more testing outside to provide a broader perspective.
Good news is we just completed the capture part of a skintone test of IQ250 vs IQ260 at each back's complete ISO range. We'll be working with Douglas Sonders to post that test along with the raws so everyone can play to their hearts delight. Probably won't be processed/evaluated/uploaded/posted for a week or so. It'd probably be faster but people keep coming in wanting demos of the IQ250, darn them! (I'm kidding of course, I enjoy working with photographers in person much more than processing images in a dark office).
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This kind of interior shooting is the kind of thing I do a lot of - long exposure, no flash and pulling up the shadows in post to avoid bracketing exposures. As you say, Doug, the beating the IQ250 files are taking in the shadows is impressive. Which back has the most accurate colours? They are quite different from one another on this showing.
Not sure comparing two different shots of snow will tell us much about colour unfortunately. :)
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I've researched sensor tech a bit and tested the files with my own LCC algorithms, and I think the IQ250 suffers quite a lot from pixel crosstalk on shifted tech wides. Pixel crosstalk means that light comes in through one color filter but angle is so low so it crosses over and gets registered in a neighbor photodiode. Red could be registered in green etc.
The most noticeable artifact of pixel crosstalk is actually not blurring of detail (the blurring of a shifted lens is larger, even great ones like the 32HR) but instead desaturation of colors.
This means, the more you shift your wide, the more desaturated colors will be. This is quite noticeable in the 32HR stitched jpeg (colors get kind of brownish and dull). Saturation can of course be restored to some extent with manual effort in photoshop (LCC can't correct it!), but this puts further stress on the dynamic range and color separation will suffer.
In other words, if color fidelity is excellent in the center of your wide angle lens, you may get color issues on the sides of your stitched ultrawide shot. This is probably something interior photographers need to consider.
As desaturation happens gradually it's hard to say anything definitive about the wide angle usability. I'm considerably less enthusiastic about combining the IQ250 with tech wides now after some analysis than I was when I first saw the test images.
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In other words the lens has to be designed to deliver highly collimated light so that the added angles of shift/tilt do not smear the light across the sensor surface at these tiny distances. Maybe enhanced microlenses can help.
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In other words the lens has to be designed to deliver highly collimated light so that the added angles of shift/tilt do not smear the light across the sensor surface at these tiny distances. Maybe enhanced microlenses can help.
More retrofocus in the lenses (Canon's TS-E 17 and 24 works great), putting photodiodes closer to the surface (backside illumination process) and possibly enhanced microlenses and lightpipes. And of course making the pixels larger would help too.
Maybe it's possible to hinder crosstalk by putting in some "walls" between pixels so light can't cross under the filter. From center to close to the edge of the image circle of the 32HR the IQ250 loses ~4 stops of signal due to pixel vignetting, I don't know how much would further be lost if crosstalk was eliminated by just letting the light smash into walls, but I think it's a fraction of a stop, otherwise desaturation issue would be larger than it is.
I don't think it's a great idea to solve the problem only with optics, ie make tech cam lenses as retrofocus as DSLR lenses, as it will then be very difficult to keep the performance edge in terms of sharpness and lack of distortion tech cams are known for, and lenses would be even larger heavier and more costly than the current 32HR.
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Hi,
Don't forget that there is a natural loss of illumination according to cos^4 that accounts for two stops alone on a 32 mm.
But you are probably right that LF-lenses and the Sony sensor are not created for each other. Leica M has a lot of issues with wide M-lenses and wide M lenses don't work well on the A7r.
Best regards
Erik
More retrofocus in the lenses (Canon's TS-E 17 and 24 works great), putting photodiodes closer to the surface (backside illumination process) and possibly enhanced microlenses and lightpipes. And of course making the pixels larger would help too.
Maybe it's possible to hinder crosstalk by putting in some "walls" between pixels so light can't cross under the filter. From center to close to the edge of the image circle of the 32HR the IQ250 loses ~4 stops of signal due to pixel vignetting, I don't know how much would further be lost if crosstalk was eliminated by just letting the light smash into walls, but I think it's a fraction of a stop, otherwise desaturation issue would be larger than it is.
I don't think it's a great idea to solve the problem only with optics, ie make tech cam lenses as retrofocus as DSLR lenses, as it will then be very difficult to keep the performance edge in terms of sharpness and lack of distortion tech cams are known for, and lenses would be even larger heavier and more costly than the current 32HR.
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Don't forget that there is a natural loss of illumination according to cos^4 that accounts for two stops alone on a 32 mm.
Yes, and the test did not use a center filter (which would improve that), but losing 3-4 stops of the signal seems to be the least of the problems as this sensor lots of dynamic range to pick from.
The different angular response on the greens and the crosstalk seem be show stoppers though, at least for the 32mm. The 40 could work but I'd want to do more testing.
If color fidelity only can be had in the central part of the image circle, the meaning is lost. I certainly prefer color fidelity over resolution, to enjoy the sharpness of a wide angle tech cam lens you need to get up close, but color you see on a distance.
Sharpness is easy to evaluate, just pixel peep. Color is harder to evaluate though, and the gradual falloff in performance is kind of nasty, it may look good on one subject but worse on another. Therefore I would be very careful before investing in a IQ250 to be used on a tech cam.
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Hi,
No argument, I essentially agree.
I would also agree that current designs are not very friendly to centric WA designs. This is quite obvious with Leica, who do a lot of SW corrections on both the M9 and the. Leica even developed (paid for development?) for their own CMOS sensor. The CMOSIS sensor has shallower wells than the Sony sensors.
For me the IQ-250 is not very interesting, to begin with, I cannot afford it. Also my route to MFD is using old Hasselblad lenses, with a Hartblei HCam on the distant horizon, so crop factor matters. MF folks always used to say that CCD-s were much better than CMOS designs, better DR, better colour and the great advantage of sixteen bit data, not that I believe any of that. Statements like that really undermine MF credibility for me. So it is interesting to see how the IQ-250 performs.
I would say that LiveView is probably nice for technical cameras, especially if combined with good peaking. LiveView is one of the things I miss on the P45+. I know that it has LV, sort of, but I don't shoot in studio (except tests) so I have little use for it as I cannot have live view on the back.
If I stay with MF I guess I would get a Hartblei HCam. Use my V-series lenses with a Mirex TS adapter and get both CanonTS lenses. But I may just skip MF and stay with Sony.
I am somewhat ambivalent about MF right now. "Where is the beef?" is the question I ask.
Best regards
Erik
Color is harder to evaluate though, and the gradual falloff in performance is kind of nasty, it may look good on one subject but worse on another. Therefore I would be very careful before investing in a IQ250 to be used on a tech cam.
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Note that RT does not have any color matrix for the IQ250 yet, which means that it just uses a default one, I think it assumes (=pretends) the RGB primaries of the camera are the same as sRGB. When we have a proper matrix the default color will be better. The IIQ format does have built-in matrix, but I'm not sure how that should be interpreted, it provides much too saturated color if just used straight away. (RT does not use the built-in matrixes for the IIQ format currently.)
That's ok, I did my own correction of the "primaries" based on what I thought was natural and flattering color. Natural comes first. I have not been in that building so if my less saturated interpretation is off I retract my use of the word enthusiastic. What do other people see? Nobody else is throwing in an interpretation. This is a rare opportunity, you have a very nice subject, a very high end camera system, at least 2 raw converters that will take it on. C1 and RT. People should be looking at what they can achieve vs their regular system.
For me, I am like Bernard, I would stick with stitching. D600 + Nikon 85 1.8G would handle this subject well. So would Sony A55 with 50 macro. Color accuracy would be a bit less, DR would be noticeably less, requiring HDR. Still, the job would get done.
The big test, as Doug has already stated, is when you put this system in a situation where you have to do it in one shot. Fast changing light or moving subject. Give us a green flash over mountains at dawn to play with!
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Hi,
I would guess that the D600 has similar DR to the IQ-250. Similar technology and larger pixels. Stitching also gives more pixels.
Sharpness from the IQ-250 on the technical camera is impressive, but comes with extensive aliasing.
Best regards
Erik
That's ok, I did my own correction of the "primaries" based on what I thought was natural and flattering color. Natural comes first. I have not been in that building so if my less saturated interpretation is off I retract my use of the word enthusiastic. What do other people see? Nobody else is throwing in an interpretation. This is a rare opportunity, you have a very nice subject, a very high end camera system, at least 2 raw converters that will take it on. C1 and RT. People should be looking at what they can achieve vs their regular system.
For me, I am like Bernard, I would stick with stitching. D600 + Nikon 85 1.8G would handle this subject well. So would Sony A55 with 50 macro. Color accuracy would be a bit less, DR would be noticeably less, requiring HDR. Still, the job would get done.
The big test, as Doug has already stated, is when you put this system in a situation where you have to do it in one shot. Fast changing light or moving subject. Give us a green flash over mountains at dawn to play with!
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I am somewhat ambivalent about MF right now. "Where is the beef?" is the question I ask.
If one like you and me not use the latest so we don't have the single shot resolution advantage to enjoy I think the joy must come from the camera. The back as I see it is just about getting adequate performance to a not-too-high price. And then it may not be using a better camera, a Hassy V or Mamiya RZ is certainly not easy to operate compared to a consumer DSLR, but it's different, a bit nostalgic and quite fun. I like my Linhof, and while I do enjoy to study new technology I don't really own much of it, I like being able to have this camera and not feeling stressed by the upgrade race, and I like the slower workflow.
However, using a Hassy V and always missing focus can be frustrating, and focusing on ground glass on my Linhof is not for all. So while I may enjoy my camera others could hate it, we're all different. If one does not really enjoy using the camera the back is attached to, ie would rather use the convenience of a DSLR, I think selling the back is a wise decision. It can't be kept just based on image quality.
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Hi,
I would guess that the D600 has similar DR to the IQ-250. Similar technology and larger pixels. Stitching also gives more pixels.
Sharpness from the IQ-250 on the technical camera is impressive, but comes with extensive aliasing.
Best regards
Erik
I think so too. The bit less DR and Color accuracy comment was for the A55.
If you look at the sorted list of cameras at DxO the D600 is #3 behind the D800E and D800. The Phase IQ180 is below the D600.
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I have deleted the alternate conversion i posted. It doesn't look like any comparisons will be coming out.
The file is quite impressive, as it should be from a camera costing as much as an SUV.
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All in all I have the feeling that the acceptance of the DxOMark results as a credible measure of real world camera performance, in particular DR, has been increased by these tests. ;)
Cheers,
Bernard
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Hi,
I don't know about DxO mark but I see that Sony Exmoor works as Sony Exmoor even in MFD, and it seems to work really well.
Best regards
Erik
All in all I have the feeling that the acceptance of the DxOMark results as a credible measure of real world camera performance, in particular DR, has been increased by these tests. ;)
Cheers,
Bernard
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Great test. I am coming from an Aptus II 12 R. I shoot product on a sinar P2. using a bass V mount. I am wanting to upgrade and get a MF system as well. With the release of the 50mp back, the higher iso is attractive. I can't seem to shoot my back above 100 without it starting to fall apart. All I really need is 400, and that would help a lot. I don't see much loss of detail between the 80 and the 50, besides the loss in megapixels. Do you see any reason not to downgrade to 50 megapixels?
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Yes I would be careful if you require movements and wide lenses on a tech camera. The 50 MP chip is not a good solution. Crosstalk and loss of color fidelity. If you are using longer lenses 90mm and up its a great solution.
DT early on reported some severe issues with the 60XL both on center and with movements. Doug was going to do more testing but I don't know if that ever occurred.
Also note that since announcement Phase One to my knowledge has not sponsored any information on with the IQ250 on a tech camera. All of their sponsorship has been on the DF+. There have been good results with the IQ250 using the Canon TS-E wides with both the Alpa FPS and Hcam. Neither a good solution for me.
Paul
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Great test. I am coming from an Aptus II 12 R. I shoot product on a sinar P2. using a bass V mount. I am wanting to upgrade and get a MF system as well. With the release of the 50mp back, the higher iso is attractive. I can't seem to shoot my back above 100 without it starting to fall apart. All I really need is 400, and that would help a lot. I don't see much loss of detail between the 80 and the 50, besides the loss in megapixels. Do you see any reason not to downgrade to 50 megapixels?
Hi Bill,
If you change your back to say the new Credo 50 (http://www.mamiyaleaf.com/credo50.html) you will see a few differences:
1. The sensor is smaller so your lenses will become a bit longer and you will gain a bit more DOF if you try to keep the same framing
2. Live View on the Credo 50 is much, much better than on your Aptus, whether you use it tethered to Capture One or on the back. The latter is very handy on the P2 as you don't have to look at the computer
3. Base iso on the Credo 50 is 100
4. Your 12R has a rotating sensor. Other backs don't have it...
Hope this helps
Yair
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Great test. I am coming from an Aptus II 12 R. I shoot product on a sinar P2. using a bass V mount. I am wanting to upgrade and get a MF system as well. With the release of the 50mp back, the higher iso is attractive. I can't seem to shoot my back above 100 without it starting to fall apart. All I really need is 400, and that would help a lot. I don't see much loss of detail between the 80 and the 50, besides the loss in megapixels. Do you see any reason not to downgrade to 50 megapixels?
As stated above, smaller sensor (longer effective length for any given lens) is the biggie. Dropping from 80mp to 50mp is a loss of resolution, but both are quite high in resolution for most applications. Ultimately only you can decide how much resolution you want and how much you need. Take some of your 80mp files and downsample them to 50mp; the result won't be exactly the same, but close enough to make an educated decision based off of. Alternatively contact a dealer and get relevant raw files from the Credo 50 or IQ250 so you can make your own processing and output and decide what you feel about the resolution.
The 50mp sensors struggle with movement on wider lenses, especially symmetrical lenses like those of Schneider, when used on a tech camera for architecture or interiors, especially when used at infinity. It's still very possible to use an IQ250 for those purposes, you're just limited to Rodenstock lenses and less movement than you could get with other backs, so in general it's not our 1st recommendation for those applications (landscape/architecture). In contrast, when shooting product about bread-box sized and smaller this isn't much of an issue - your focus distances mean that the lens is quite far from the sensor and the amount of movement usually isn't as significant as with architectural/interior and it's less common to use very wide lenses. We did some fairly extensive testing for a client who exclusively shoots table top product; in his case (meaning the lenses, focus distances, and amount of movement that were typical for him) the color cast was not deemed an issue on either back and the significantly improved live view won the day.
My suggestion, which is transparently selfish, but I think a good suggestion none the less, is to work with a dealer which has done extensive testing on these questions, and communicate to them exactly what kinds of lenses, movements, and focus-distances you use and they can let you know if you're barking up the right tree. If you fall outside the "clearly okay" or "clearly a problem" ranges then arrange to do testing at their facilities, or arrange a rental through them to do testing at your own studio.
But really, for live view, you'll be amazed at how nice the USB3 based Live View is on a large monitor (or also on the back itself in the case that you're arranging items in front of the camera and don't want to crane your neck to see the monitor).
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Hi,
Seems to me like a good and honest analysis, what I would expect from Doug :-)
Best regards
Erik
As stated above, smaller sensor (longer effective length for any given lens) is the biggie. Dropping from 80mp to 50mp is a loss of resolution, but both are quite high in resolution for most applications. Ultimately only you can decide how much resolution you want and how much you need. Take some of your 80mp files and downsample them to 50mp; the result won't be exactly the same, but close enough to make an educated decision based off of. Alternatively contact a dealer and get relevant raw files from the Credo 50 or IQ250 so you can make your own processing and output and decide what you feel about the resolution.
The 50mp sensors struggle with movement on wider lenses, especially symmetrical lenses like those of Schneider, when used on a tech camera for architecture or interiors, especially when used at infinity. It's still very possible to use an IQ250 for those purposes, you're just limited to Rodenstock lenses and less movement than you could get with other backs, so in general it's not our 1st recommendation for those applications (landscape/architecture). In contrast, when shooting product about bread-box sized and smaller this isn't much of an issue - your focus distances mean that the lens is quite far from the sensor and the amount of movement usually isn't as significant as with architectural/interior and it's less common to use very wide lenses. We did some fairly extensive testing for a client who exclusively shoots table top product; in his case (meaning the lenses, focus distances, and amount of movement that were typical for him) the color cast was not deemed an issue on either back and the significantly improved live view won the day.
My suggestion, which is transparently selfish, but I think a good suggestion none the less, is to work with a dealer which has done extensive testing on these questions, and communicate to them exactly what kinds of lenses, movements, and focus-distances you use and they can let you know if you're barking up the right tree. If you fall outside the "clearly okay" or "clearly a problem" ranges then arrange to do testing at their facilities, or arrange a rental through them to do testing at your own studio.
But really, for live view, you'll be amazed at how nice the USB3 based Live View is on a large monitor (or also on the back itself in the case that you're arranging items in front of the camera and don't want to crane your neck to see the monitor).